Doped Tio <sub> 2 </ Sub> Preparation And Photocatalytic Properties

Titanium dioxide (TiO2) with excellent catalytic activity and photoelectric characteristic, is a kind of important inorganic function materials. However, TiO2with its band gap3.2eV and absorption edge less than380nm has photoactivity only under ultraviolet(UV) light. Thus, only a small portion of the solar energy can be utilized, Which increases its application cost seriously. This is the main reason why TiO2has not been widely used commercially. In recent years, theoretical and experimental studies have indicated that optical absorption of doping modification TiO2obviously enhanced in the visible region, and its light catalytic reaction efficiency greatly increased in the sun. Thus TiO2became ideal material in photocatalytic reaction, and was concerned more and more.In this paper, series of Fe doped TiO2samples had been prepared by sol-gel method or precipitation method, and the Fe doping TiO2sample prepared by precipitation method was burned in the nitrogen pressure again for0.01～0.02MPa atmosphere,(Fe,N) codoping TiO2could be got. The samples were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), ultra violet-visible (UV-vis) and kjeltec auto analyzer. Molecular structure, crystal structure and photocatalytic capability of Fe doping and (Fe,N) codeping TiO2had been systematically emphasized. The main works and results are as following.(1) In Fe doped TiO2samples prepared by sol-gel method. There is a litter C element in the samples prepared by sol-gel method. Chemical environment around O element is changed with being doped, three chemical state of O are existed. There are many hydroxyl groups on the surface of doped samples, photocatalytic performance can be improved. Ti is in the form of Ti4+, and the binding energy of Ti2p increase because of Fe doped. The phase transformation temperature of anatase to rutile is500℃～600℃, the temperature is low. The absorption edge of the sample with Fe content1.0%and600℃shift to visible spectral range, band gap is2.75eV, absorption edge is451nm, well visible light activity is displayed.(2) There is no rutile phase in the sample prepared by precipitation method sintered at700℃, doped Fe don't change the crystal structure of TiO2, with temperature and doping content increasing, more and more hydroxyl groups could be adsorbed by the samples. And absorption edge were red shift in varying degrees, optical activity of TiO2is improved by Fe doped. The dispersity of powder was improved obviously after doped, specific surface area is large and catalytic effect is higher. The elements of Ti, O and Fe in the sample can be test by EDS. In different temperature, band gap of the sample with Fe content1.0%and700℃is2.95eV, absorption edge is420nm, well visible light activity is displayed. In different Fe content, band gap of the sample with Fe content1.5%and600℃is2.70eV, absorption edge is458nm.(3) The Fe doped TiO2sample was burned in the nitrogen pressure again for0.01～0.02MPa atmosphere,(Fe,N) codoped TiO2can be got. After burning in N2atmosphere, N content of the samples is rising from0.04wt%to0.17wt%, and there are many rutile phase in the sample burned at700℃. There are16.05%rutile with600℃and1.5%Fe content. And the phase transformation temperature decrease because of Fe,N synergy effect, absorption edge is418nm, photocatalytic capability of the samples is enhanced.